Insight article
Locking into Harmony: how bubble science is changing the game
23 May 2025
The spark that started it
Harmony came to life with a challenge that sparked a bold idea. When energy companies started to call for a low-frequency source in tenders, it quickly became clear that access to the necessary technology via third-party vendors was limited—and the associated costs were simply uneconomical. It forced a moment of pause and rather than accepting the status quo, we questioned—could we do this better ourselves?
That moment brought together Bjarne Stavnes, a field-proven expert with deep operational experience, and Susanne Rentsch, a driven geophysicist with a passion for pushing technical boundaries. Together, they saw an opportunity to initiate bold innovation.
They revisited a promising frequency-locking phenomenon and saw the potential to bring it to life in a way no one had yet managed. More importantly, they believed in something bigger—that the combined expertise across the company, spanning engineering, geophysics, operations, and technology, was exactly what it would take to make this work
Backing them was Mehul Supawala at Shearwater’s Technology and Innovation Center, giving the green light to pursue the project. It wasn’t sure to succeed . But it was grounded in science, operational insight, and a genuine appetite for smarter seismic.
The traditional trade-off
In seismic acquisition, there has always been a catch. If you want to output more low-frequency signals, you have to go big. Really big.
Conventional approaches for outputting more low-frequency energy required chamber volumes up to 20–25 times larger than what's typically used in standard arrays. That scale brought serious trade-offs in size, complexity, and cost—not to mention a potential redesign of the entire source system.
At Shearwater, we took a different path. Instead of asking "How do we go bigger?" we asked "How do we go smarter?"
That shift in thinking unlocked a completely different solution.
What if, instead of avoiding bubble interaction in the pressure field of a standard array, we use it? What if each air sources pressure field can enhance the others, letting the system act as one coherent volume? That idea—frequency locking—was known science, but no one had fully engineered it into a towed marine source. Until now.
Teamwork from concept to prototype
Harmony was only possible thanks to close collaboration between specialists across geophysics, engineering, operations, and field execution—each playing a crucial role in turning the idea into reality.
Susanne Rentsch simulated pressure field interactions across various volumes and configurations to identify a “Goldilocks zone”—a sweet spot that balances low-frequency output, refill time, air source volume, and operational robustness.
Building on this, Ola Larsen, responsible for simulations, modelled the system around the identified sweet spot, evaluating mechanical stresses and guiding the engineering design to ensure long-term robustness and reliability in the field.
Next, senior project engineer Helge Teigland engineered custom chambers designed to hold the required air volumes, with rods strong enough to withstand the immense forces involved in releasing such a significant amount of air. And Bjarne Stavnes, Operational Lead, knew exactly the right workshop to produce them—reliably and quickly—ensuring the components were ready for testing without delay.
Shortly after, Chris Field, Senior Mechanic and offshore build lead, and his team of skilled mechanics dove in, building the first-ever Harmony unit. With no blueprint to follow and high stakes on the line, the tension was unmistakable—but their determination, expertise, and innovation brought the groundbreaking source to life.
And it was big. Instead of the usual 2x 290 cu.in. setup, they were looking at 2x 1000 cu.in. per cluster. They were tasked to build 3 clusters—six elements in total.
Chris Field remembers:
“When I first saw the brief, it felt almost unreal. Could the equipment handle this? The first shot answered every question. It worked.”
As Harmony was deployed for the first time, everyone crossed their fingers—maybe even toes—for peak stress predictions to hold true and the units to survive the test.
When the first Harmony shots fired at sea, Eldar Guliyev, Field observation, watched from a sister ship during a seabed acquisition.
Eldar recalls:
“From the sister ship, we had a front-row seat. When those massive bubbles broke the surface, you could feel the tension snap. Everyone rushed to the rail—filming, pointing, cheering. It looked different, it felt different. We all knew something big had just happened.”
It was a literal breakthrough, and a symbolic one too. The deep rumble, the burst of bubbles, the reaction—it all confirmed what the team had hoped for. Harmony was real, and it had just made a big entrance.
Built in a pandemic, designed for practicality
This wasn’t a blue-sky R&D project. It was designed under unprecedented constraints.
In the middle of the COVID pandemic, with supply chains collapsing or strained, new or special parts were near impossible to come by with reasonable commercials and lead times. Shearwater took a practical route by reusing existing parts where possible.
Apart from the volume chambers and cluster bars, Harmony was built with standard kit. That made it not only inventive, but accessible, scalable—and crucially, compatible with existing source strings across the entire fleet.
That meant minimal training, minimal changes, and no need for new source strings.
Making it seaworthy
A unique sea trial opportunity soon followed: a vessel in transit to a delayed job offered time and crew. Harmony went offshore again with an experienced crew of top-notch observers, navigators, mechanics, and one geophysicist.
The goal? Not just to fire the sources, but to get the right signal, repeatably, shot after shot, in a safe and operationally viable manner.
“It wasn’t just about getting the signal,” Susanne Rentsch says. “It had to be safe, stable, and fleet-ready.”
For three weeks, it acquired data nearly non-stop. The endurance test proved what the modelling had suggested all along: Harmony wasn’t just clever- it was robust and tough, and delivered the desired low frequencies as predicted.
Stein-Åge Blakstad, Lead STH support engineer, led the towing setup supported by Carlos Barreto and his team of offshore menchanics, ensuring Harmony could be safely launched, towed, and recovered.
Lauren Wing, the offshore geophysicist on duty, kept eyes on the data—monitoring the source in real time together with the navigators and observers running a multitude of tests.
The reward? She was the first to see and confirm: consistent frequency locking, repeatable performance, and—crucially—the viable refill times that were thus far only predicted on paper. It was a defining moment. The theory was holding up in the real world.
With Harmony, we now have a proven, in-house solution—born from necessity, shaped by expertise, and built to give us back control over access to low-frequency rich sources on our own terms.
The build challenges (and workarounds)
Chris Field's team faced hurdles. Mounting chambers that big using the old vertical-lift method didn’t work. So they thought outside the box, breaking from traditional assembly.
They pre-mounted the two chambers on the cluster bars and lowered the whole assembly in one go, perfectly square, using a chain hoist. Alignment was spot-on. Seals were preserved.
Then came the camera work. To validate Harmony properly and to assess the stability of the system, they needed bubble footage. They built rugged housings and mounted two cameras: one forward, one aft. The footage showed not just performance, but stress points—like the way pigtails were whipped about during firing. That helped shape improvements for the next deployment.
What makes Harmony different from conventional sources
- Frequency locking: six smaller sources acting like one giant source
- Downward shift: half to one octave lower in dominant frequency
- Cleaner signals: less high-frequency waste, more useful energy
- Standard parts: safer, more available, easier to maintain
- Fleet ready: integrates with existing arrays across all vessels
Client-proven
While Harmony proved its worth in many prolific basins, the best proof is always when its added value is validated by a client.
Off the coast of Malaysia, Harmony ran in hybrid mode alongside a conventional source, imaging beneath complex carbonates where other tools had struggled.
The client wanted it all: deeper penetration, better resolution, improved imaging and enhanced signal – to – noise ratio and all that without adding operational complexity or turnaround time. Harmony delivered and the client published the results
Onboard SW Thuridor, the team ran a smooth survey, safely and on time. The data showed better velocity models, better imaging, and better subsurface definition. That meant better decisions.
Why it matters
Harmony is seismic thinking in action. It shows what happens when you bring together geophysics, engineering, and operational know-how to ignite a spark. When you listen to the field. When you dare to try a new approach.
At Shearwater, this is how we work. Practical, pioneering, and powered by science, operational excellence, and great people.
Ready to deploy
Harmony is available now, across our fleet. It’s ready for your next survey, whether you're targeting carbonates, running a hybrid survey, or just need a deeper, clearer signal without a fleet overhaul.
Let’s talk about how Harmony can support your next seismic mission.
The minds behind Harmony
- Susanne Rentsch – Program Manager and Lead Geophysicist
- Bjarne Stavnes – Operational Lead
- Mehul Supawala – Project Sponsor
- Helge Teigland – Chamber Design
- Ola Larsen – Simulations
- Christopher Field and team – Prototype Build
- Stein-Åge Blakstad and team – Handling and Towing
- Carlos Barreto and team – Offshore Mechanical Qualification
- Lauren Wing and skilled observers and navigators – Offshore Geophysical Qualification
- Eldar Guliyev – Field Observation
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